“活性炭表面改性及对苯的吸附研究”综合性实验设计

为加强学生对吸附单元操作基础知识的理解、提升实验研究技能,设计了“活性炭表面改性及其苯吸附性能研究”综合性实验项目。该项目设立了吸附剂基本性质分析、表面改性、吸附性能表征及动态吸附等内容,分别训练学生实验研究、实验操作、仪器表征、图谱解析及实验结果总结分析的能力。经过实验训练,学生掌握了N2吸/脱附仪、傅里叶变换红外光谱仪(FTIR)和扫描电子显微镜(SEM)的仪器操作与图谱解析方法;学会了表面改性实验及活性炭碘吸附值、亚甲基蓝吸附值和动态吸附性能测试的实验方法与结果的归纳分析;还结合所学吸附单元操作基本原理,研究揭示实验研究的规律性结果。本综合性实验在加强学生对吸附单元操作相关知识掌握的同时,能激发学生的学习兴趣、提升专业综合能力。

Preparation of pitch precursor with excellent spinnability for general-purpose carbon fibre using coal tar pitch as raw material

Tetrahydrofuran(THF) extract of coal tar pitch(CTP) was used instead of blending CTP with pretreated pyrolysis fuel oil to prepare an isotropic pitch precursor with excellent spinnability for general-purpose carbon fibre through bromination-dehydrobromination. The feasibility and effectiveness of synthesising an isotropic pitch precursor derived from THF-soluble(CTP-THFs) is demonstrated in this study.The results show that CTP-THFs contains more light components than CTP;CTP-THFs and CTP monomer proportions were 62.52% and 45.32%, respectively. However, based on comparisons of CTP-THFsBr0 and CTPBr0 characterisations, CTP-THFs exhibits better polycondensation than CTP. Bromination-dehydrobro mination promotes polycondensation of pitch precursors, leading to greater carbon aromaticity in CTP-THFsBr5, CTP-THFsBr10, and CTP-THFsBr15 than that in CTP-THFsBr0 and CTPBr0. CTP-THFsBr5 and CTP-THFsBr10 have excellent spinnability even with softening points as high as 230 ℃. The pericondensed carbon and carbon aromaticity of CTP-THFsBr5 and CTP-THFsBr10 are high owing to the higher degree of polycondensation;however, they still possess a more linear molecular structure. The as-prepared carbon fibre exhibits homogeneity and uniformity, and the mechanical performance is comparable with that of commercial general-purpose carbon fibre products.

Flexibility analysis and design of heat exchanger network for syngas-to-methanol process

The heat exchanger network(HEN)in a syngas-to-methanol process was designed and optimized based on pinch technology under stable operating conditions to balance the energy consumption and economic gain.In actual industrial processes,fluctuations in production inevitably affect the stable operation of HENs.A flexibility analysis of the HEN was carried out to minimize such disturbances using the downstream paths method.The results show that two-third of the downstream paths cannot meet flexibility requirements,indicating that the HEN does not have enough flexibility to accommodate the disturbances in actual production.A flexible HEN was then designed with the method of dividing and subsequent merging of streams,which led to 13.89%and 20.82%reductions in energy consumption and total cost,respectively.Owing to the sufficient area margin and additional alternative heat exchangers,the flexible HEN was able to resist interference and maintain production stability and safety,with the total cost increasing by just 4.08%.

Building of a ton-scale liquid argon prototype detector

Background Based on the unique PSD characteristic which essentially relies on the detector light yield,liquid argon detector is widely used for dark matter searching experiment.The experimental study of how to get larger light yield for a ton-scale liquid argon detector is worth to be carried out.Purpose A ton-scale liquid argon prototype detector is built to check the detector implementation as well as the light collection efficiency.Methods A ton-scale single-phase liquid argon prototype detector is built in the surface laboratory for scalable detector construction experience.The detector adopts the classical spherical arrangement mode to obtain a large PMT photocathode coverage.Forty-two PMTs are immersed in the liquid argon,and polymer materials are used to construct the PMT supporting structures.Totally about 2.2 tons of liquid argon is used,of which about 160 kg is the active volume.In this paper the details of the experiment as well as the detector performance are introduced.Results Experiment results show that the light yield reaches 6.3 PE/keV,with an effective photon collection efficiency of 74.3%achieved.

Correction to:Building of a ton-scale liquid argon prototype detector

Correction to:Radiation Detection Technology and Methods https://doi.0org/10.1007/s41605-023-00427-8 Page 3,column 1,para 3 under heading The cryogenic system,the word which previously read as.

JUNO sensitivity on proton decay p→νK^(+)searches

The Jiangmen Underground Neutrino Observatory(JUNO)is a large liquid scintillator detector designed to explore many topics in fundamental physics.In this study,the potential of searching for proton decay in the p→νK^(+)mode with JUNO is investigated.The kaon and its decay particles feature a clear three-fold coincidence signature that results in a high efficiency for identification.Moreover,the excellent energy resolution of JUNO permits suppression of the sizable background caused by other delayed signals.Based on these advantages,the detection efficiency for the proton decay via p→νK^(+)is 36.9%±4.9%with a background level of 0.2±0.05(syst)±0.2(stat)events after 10 years of data collection.The estimated sensitivity based on 200 kton-years of exposure is 9.6×1033 years,which is competitive with the current best limits on the proton lifetime in this channel and complements the use of different detection technologies.

Accelerating local SGD for non-IID data using variance reduction

Distributed stochastic gradient descent and its variants have been widely adopted in the training of machine learning models,which apply multiple workers in parallel.Among them,local-based algorithms,including Local SGD and FedAvg,have gained much attention due to their superior properties,such as low communication cost and privacypreserving.Nevertheless,when the data distribution on workers is non-identical,local-based algorithms would encounter a significant degradation in the convergence rate.In this paper,we propose Variance Reduced Local SGD(VRL-SGD)to deal with the heterogeneous data.Without extra communication cost,VRL-SGD can reduce the gradient variance among workers caused by the heterogeneous data,and thus it prevents local-based algorithms from slow convergence rate.Moreover,we present VRL-SGD-W with an effectivewarm-up mechanism for the scenarios,where the data among workers are quite diverse.Benefiting from eliminating the impact of such heterogeneous data,we theoretically prove that VRL-SGD achieves a linear iteration speedup with lower communication complexity even if workers access non-identical datasets.We conduct experiments on three machine learning tasks.The experimental results demonstrate that VRL-SGD performs impressively better than Local SGD for the heterogeneous data and VRL-SGD-W is much robust under high data variance among workers.

Feasibility and physics potential of detecting ^(8)B solar neutrinos at JUNO

The Jiangmen Underground Neutrino Observatory(JUNO)features a 20 kt multi-purpose underground liquid scintillator sphere as its main detector.Some of JUNO's features make it an excellent location for^8B solar neutrino measurements,such as its low-energy threshold,high energy resolution compared with water Cherenkov detectors,and much larger target mass compared with previous liquid scintillator detectors.In this paper,we present a comprehensive assessment of JUNO's potential for detecting^8B solar neutrinos via the neutrino-electron elastic scattering process.A reduced 2 MeV threshold for the recoil electron energy is found to be achievable,assuming that the intrinsic radioactive background^(238)U and^(232)Th in the liquid scintillator can be controlled to 10^(-17)g/g.With ten years of data acquisition,approximately 60,000 signal and 30,000 background events are expected.This large sample will enable an examination of the distortion of the recoil electron spectrum that is dominated by the neutrino flavor transformation in the dense solar matter,which will shed new light on the inconsistency between the measured electron spectra and the predictions of the standard three-flavor neutrino oscillation framework.IfDelta m^(2)_(21)=4.8times10^(-5);(7.5times10^(-5))eV^(2),JUNO can provide evidence of neutrino oscillation in the Earth at approximately the 3sigma(2sigma)level by measuring the non-zero signal rate variation with respect to the solar zenith angle.Moreover,JUNO can simultaneously measureDelta m^2_(21)using^8B solar neutrinos to a precision of 20% or better,depending on the central value,and to sub-percent precision using reactor antineutrinos.A comparison of these two measurements from the same detector will help understand the current mild inconsistency between the value of Delta m^2_(21)reported by solar neutrino experiments and the KamLAND experiment.

Sub-percent precision measurement of neutrino oscillation parameters with JUNO

JUNO is a multi-purpose neutrino observatory under construction in the south of China.This publication presents new sensitivity estimates for the measurement of the △m_(31)^(2),△m_(21)^(2),sin^(2)θ_(12),and sin^(2)θ_(13) oscillation parameters using reactor antineutrinos,which is one of the primary physics goals of the experiment.The sensitivities are obtained using the best knowledge available to date on the location and overburden of the experimental site,the nuclear reactors in the surrounding area and beyond,the detector response uncertainties,and the reactor antineutrino spectral shape constraints expected from the TAO satellite detector.It is found that the △m_(21)^(2) and sin^(2)θ_(12) oscillation parameters will be determined to 0.5%precision or better in six years of data collection.In the same period,the △m_(31)^(2) parameter will be determined to about 0.2%precision for each mass ordering hypothesis.The new precision represents approximately an order of magnitude improvement over existing constraints for these three parameters.